Circuit breaker



April 12, 1966 w. J. PENDY, JR., ETAL 3,246,097

C IRCUI T BREAKER Filed Sept. 27, 1963 2 Sheets-Sheet l und Nick YorginBY (I WM w. awa

ATTORNEY April 12, 1966 w. J. PENDY, JR., ETAL 3,246,097

CIRCUIT BREAKER Filed Sept. 27: 1,965

2 Sheets-Sheet 2 United States Patent O 3,246,097 CIRCUIT BREAKERWilliam J. Pendy, Jr., Chippewa Township, and Nick Yorgin, Economy, Pa.,assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Filed Sept. 27, 1963, Ser. No. 312,127 7Claims. (Cl. 20G-88) This invention relates generally to circuitbreakers and more particularly to circuit breakers for controllinglighting and moderate power circuits.

Some types of circuit breakers are constructed with a rigid andstationary stop that is engaged by the movable contact structure tolimit opening movement of the movable contact structure. During normalmanual on and oil operations, this means for stopping the movablecontact structure is generally satisfactory. During automatic circuitinterruption, however, the opening movement of the movable contactstructure is highly accelerated by magnetic forces generated by theoverload current that is being interrupted. When the highly acceleratedmovable contact structure hits a solid stop, it rebounds, in someinstances as much as 6/7 of the original opening distance, toward theclosed position to sometimes cause a restriking of the arc therebydelaying interruption of the damaging overload.

An object of this invention is to provide a circuit breaker withimproved means for arresting rebound of the movable contact structureduring automatic opening operations.

Another object of this invention is to provide an improved standard typeof circuit breaker with improved relatively simple and inexpensive meansfor arresting rebound of the movable contact structure during automaticopening operations.

A further object of this invention is to provide a circuit breaker withimproved means for arresting rebound of the movable contact structureand for nally stopping the parts with the handle positioned to provide aVisual indication that the breaker has tripped.

The invention, both as to structure and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description when read in conjunction with theaccompanying drawings:

FIGURE 1 is a vertical sectional view of the center pole of a three-polecircuit breaker embodying the principals of this invention;

FIGS. 2, 3 and 4 are side views, with parts broken away, of certainparts of the circuit breaker mechanism illustrating relative positionsof the parts during an automatic opening operation.

The invention is illustrated as applied to a circuit breaker of the typedisclosed in the patent to E. A. Walker, et al., Patent No. 2,989,606,issued lune 20, 1961, and assigned to the assignee of the instantapplication.

Referring to FIGURE 1 of the drawings, there is shown therein the centerpole unit of a three-pole circuit breaker 1. The circuit breaker 1comprises a base 11 and a cover 13 both of molded insulating material. Astationary contact 15 and a cooperable movable contact 17 are providedfor each pole of the breaker. An operating mechanism 19, common to allof the poles, is disposed in the center pole compartment. Each of thethree poles is provided with a trip device 21.

The stationary contact 1S, for each pole, is rigidly mounted on theinner end of a conducting strip 23, the outer end of which is secured bymeans of a line terminal connector to a metal insert 26 that is seatedin the base 11. The movable contact 17 is part of a movable coni3,246,097' Patented Apr. 12, 1966 ICC tact structure indicated generallyat 27 that comprises a contact arm 28 having the contact 17 secured tothe outer end thereof. The contact arm 28 is pivotally secured to aswitch arm 29 by means of a pin 30. The switch arm 29 comprises twoidentical arms having the contact arm 28 supported therebetween. Theswitch arm 29 is rigidly secured to an insulating tie bar 35. The tiebar 35 is rotatably supported in the sidewalls of the two outer poles.Each pole comprises a movable contact structure 27 that is rigidlysecured to the common tie bar 35. Each of the contact arms 28 is biasedin a clockwise direction about the associated pin 30 by means of atorsion spring 36. In each pole, a pin 37 is secured to the switch arm29 between the twin members of the switch arm. The pin 37 is disposed ina slot 38 at the inner end of the contact arm 28 and it engages oppositeends of the slot to limit pivotal movement of the contact arm 28 aboutthe switch arm 29. The pin 37 in the center pole unit also pivotallyconnects a toggle link 40 to the center-pole switch arm 29.

The toggle link 40 is part of a single operating mechanism 19 that isdisposed in the center pole compartment and that comprises an invertedU-shaped operating lever 41 having its legs pivotally supported ingenerally V- shaped notches 43 in a pair of spaced metal frame members45 that are mounted in the bottom portion of the base 11.

The operating lever 41 has an arcuate insulating shield 47 mounted onthe outer end thereof. A handle portion 49 extends out from the shield47 through an opening 51 in the cover 13. The switch arm 29, for thecenter pole unit, is operatively connected to a releasable member orcradle 57 by means of a toggle comprising the toggle link 40 and atoggle link 58. The toggle link 40 is pivotally connected to the switcharm 29 by means of the pivot pin 37. The toggle link 58 is pivotallyconnected to the releasable member 57 by means of a pivot pin 59. Thetoggle links 40 and 58 are pivotally connected together by means of aknee pivot pin 61. The releasable member 57 is pivotally supportedbetween the side plates 45 by means of a pivotal pin 63 that isrotatably supported on and between the side plates 45. Over centersprings 67 are connected under tension between the knee pivot 61 of thetoggle 40, 58 and the yoke portion of the operating lever 41.

The contacts for all of the poles are manually opened and closed in awell-known manner by movement of the operating lever 41. When theoperating lever 41 is moved from the on to the off position, thetensioned springs 67 are moved over-center with respect to the toggle4G, 5S to cause collapse of the toggle to thereby rotate the tie bar 3Sin a counterclockwise direction moving all three of the contact armstructures 27 to an open position with a snap action. When the contactarm structure 27 for the center pole unit reaches the full openposition, a stop portion 70 thereon engages a stop portion 71 on thereleasable member 57 to limit this opening movement. During the openingmovement of the movable `Contact structure 27, the contact arm 28 movesa limited amount in a clockwise direction about the pivot 30 whichmovement is limited by the engagement of the pin 37 in the lower end ofthe slot 38 that is disposed at the inner end of the contact arm 28. Thecontact arm structures 27 for the two outer poles y(not shown) engagesuitable stop pins disposed in the outer poles to limit the openingmovement of these contact arm structures. Movement of the operatinglever 41 from the off position to the on position moves the springs 67over-center to reset the toggie 40, 58 rotating the tie bar 35, andtherefore the three movable contact structures 27, in a clockwisedirection `to the closed position with a snap action. When the movablecontact structures 27 are in the closed position (FIG. l) each of thecontact arms 23 is rotated slightly in the clockwise direction about thepin 30 to thereby permit the associated torsion spring 36 to bias theassociated contact arm 23 into the fully closed position. Thus,independent resilient contact pressure means is provided in each ot thepole units of the circuit breaker.

The contacts are opened automatically, in response to an overloadcurrent occurring in any pole of the circuit breaker, by release of thereleasable member 57. The member 57 is normally releasably restrained inoperative position by means of a latch mechanism indicated generally at72, which latch mechanism is actuated by the trip device 21. Whenreleased, the member 57 is rotated in a clockwise (FIG. 1) directionabout its pivot 63 by the torce of the discharging tensioned over-centersprings 67 causing collapse of the toggle 40, 58 and opening movement ofall of the movable contact structure 27 in a manner to be hereinafterspecifically described.

The latch mechanism 72 comprises a main latch 73 pivoted on a pin 75that is supported between the sfde plates 45. The main latch 73 isbiased in a clockwise unlatching direction by means of a torsion spring77. The main latch 73 is provided `with a latching portion 79 thatengages a latch tip 81 on the free or latching end ot the releasablemember 57 to releasably hold the member 57 in operative position. Thelatch tip S1 is in-turned in the direction toward the pivot 63 aboutwhich it moves. The latch 73 is of the slip-oit type and is releasablyheld in latching position by a latch which comprises a rotary shaft orro-d 83 that is rotatably mounted between the side plates 45. The latchrod 83 has a cut-out portion or notch (not shown) provided therein. Apart 86 of the latch 73 engages the periphery of the shaft 83 just abovethe notch. The latch 83 has an upwardly extending arm 89 secured theretowhich, at its upper end, has an ear 91 formed thereon. An adjustingscrew 93 is -threaded into the ear 91 and is rotated to an adjustedposition in engagement with a projection 97 on an insulating trip bar99. A spring 100 biases the arm 89 and the shaft 33 to the latchingposition seen in FIGURE 1.

The trip bar 99 is rotatably supported by means of pins 101 molded atthe opposite ends thereof, which -pins are rotatably supported in thesidewalls of the circuit breaker housing. The trip bar 99 is providedwith a downwardly extending projection 105 in each pole unit. In eachpole unit, an ambient temperature compensating bimetal element 107 isrigidly mounted on the projection 105 and is adapted to be mechanicallyactuated by the trip device 21 in the associated pole.

The tri-p device 21 for each pole comprises a tripping bimetal element109 that is supported on a conductor 111 that is mounted on a metallicinsert 113 which insert is secured in the base 11 during the moldingoperation of 4the base. The conductor 11 is secured on the insert 113 bymeans of a screw 115 that also secures a xed magnetic member 117 and aterminal 119 on the base. A calibrating or adjusting screw 121 issupported on a conducting tab 122 that is secured to the upper end ofthe bimetal 109. Upon thermal bending of the bimetal 199 in respouse tolow overload currents, the screw 121 engages the free or upper end ofthe compensating bimetal 107 to rotate the trip bar 99 in a clockwisedirection about the pivot 101. A magnetic member or armature 123 isrigidly secured to the tripping bimetal element 109 adjacent the upperend of the tixed magnetic member 117 and on the side of the bimetal 109that is opposite the side that faces the magnetic member 117. Thearmature 123 is attracted to the xed magnetic member 117 in response toexcessive overload currents tlowing through the bimetal 109 whereuponthe tripping bimetal 109 is bent to the right to ettect instantaneousoperation of the trip bar 99.

In each pole, a flexible conductor 125 is connected at one end to theassociated terminal 119 and at the other end to the associated contactarm 28. In each pole, a

flexible conductor 129 is connected at one end to the conducting tab 122and at the other end to a conducting strip 131.

In each pole, the circuit extends from the conductor 131 through theconductor 129, the tab 122, the bimetal 109, the conductor 111, theconductor 119, the flexible conductor 125, the contact arm 28, thecontacts 17, 15 to the Conductor 23. The conducting strip 131 for eachpole is provided at its outer end with a load terminal connector 133that is threadedly supported in a metallic i11- sert 134i that is seatedin the base 11.

The high expansion sides of the tripping bimetal element 11,19 and thecompensating bimetal element 107 are both on the left side of thebimetal elements as seen in FIGURE 1. Thus, the bimetal elements willsimultaneously deliect in the -same direction in response to changes inambient temperature to thereby compensate for thermai reaction of thetripping bimetal element 109 in response to changes in the ambienttemperature.

When a low persistent overload current below a predetermined valueoccurs in any ot the pole units, the actuating bimetal 109 in theoverloaded pole unit becomes heated and bends to the right. During thismovement, the screw 121 is moved to move the compensating bimetal 107 tothereby pivot the trip bar 99 clockwise whereupon the projection 97 onthe trip bar, engaging the adjusting screw 93, rotates the arm S9 androtary latch S3 clockwise to a position where the portion 86 of the mainlatch 73 falls into the notch (not shown) in the latch 83. rhisclockwise unlatching movement of the latch 73 frees the latch portion 81of the member 57 to release the member 57. The latching point 79 of themain latch 73 and the latch portion $1 of the member 57 are to the leftof the pivot 75 so that the main latch 73 is biased in the unlatchingdirection by a component of the force exerted by the over-center springs67. Thus, when the main latch 73 is released, it is immediately snappedto the unlatching position releasing the member 57.

When the member 5'7 is released, the tension springs 67 operate throughthe knee pivot 61, the toggle link 5S and the pin 59 to exert a force onthe member S7 rotating the member 57 about the pivot 63. During thismovement, the lever 41, springs 67, toggle 40, 5S, and movable contactstructure 27 are moved to position these parts such that the springs 67are over-center on the lett of the toggle 40, 5S whereupon the springs67 pull the kneepivot 61 upward collapsing the toggle 40, 5i; androtating the center-pole movable contact structure 27 counterclockwise,which movement, through the common tie bar 35, rotates all of themovable contact structures 27 counterclockwise to the open position witha snap action.

Improved means are provided for arresting rebound ot' the movableContact structures 27 during an automatic opening operation. Referringto FIGS. 2-4, as the movable contact structure 27 tor the center poleunit appreaches the fully opened position, the Contact arm at 137engages a projection 139 that is formed integrally with the releasablemember 57. During the automatic opening operation, the dischargingsprings 67 operate through the toggle 40, 58 to rotate the releasablemember 57 in a clockwise direction, and at the same time the springsoperate to collapse the toggle 40, 58 to thereby rotate the movablecontact structure in a counterclockwise opening direction. The openingmovement of the movable Contact structure 27 is highly accelerated bythe magnetic blow-off forces that are generated by the overload currentthat is being interrupted. Thus, when the contact arm at 137 engages theprojection 139 (FG. 2) of the releasable member 57, the clockwisemovement of the member 57 is stopped and the member 57 is thereaftermoved in a counterclockwise direction to the position seen in FG. 3.Since the member 57 is stopped and thereafter moved counterclockwiseagainst the spring force that tends to rotate this member clockwise,this action operates to decelerate opening movement of the movablecontact structure 27 to thereby arrest rebound of the movable contactstructure. In this embodiment the part 70 of the contact arm 28 engagesthe part 71 of the releasable member 57, and since the opening force ofthe movable contact structure 27 operates at 71 through the pivot 63 ofthe member 57, the part 71 of the member 57 serves as a iinal stoppreventing further counterclockwise movement of the movable Contactstructure 27.

During an automatic opening operation, the parts move from the FIGURE 1position to the FIG. 2 position wherein the movable contact structure 27engages the part 139 of the releasable member 57 to decelerate move mentof the movable contact structure 27. During this movement the springs 67also tend to rotate the lever 41 counterclockwise which movement islimited by the engagement of a tail part 143 on the lever 41 with ashoulder 14S on the releasable member 57 and by the engagement of thebight portion 147 of the generally U-shaped lever 41 with a stop portion149 on the releasable member 57. The parts then move to the FIG. 3position where, in this embodiment, the part 70 of the movable contactstructure 27 engages the part 71 of the releasable member 57 to limitopening movement of the movable contact structure 27. During thismovement, the part 147 of the lever 41 moves away from the part 149 ofthe member 57 a small distance while the part 143 of the lever 41 slidesagainst the shoulder 145 of the member 57. In the FIG. 3 position thesystem is ready to dissipate the potential energy contained in thesprings 67 at the natural frequency of vibration of this mechanicalsystem.

FIG. 4 illustrates the stopped position of the parts after an openingoperation. The component of spring force acting to rotate the member 57clockwise is stronger than the component of spring force acting torotate the movable contact structure counterclockwise. Thus, the member57 rotates clockwise until it is stopped when the part 149 thereonengages the part 147 of the lever 41. 'This engagement of the parts 149and 147 stops all of the parts in the FIG. 4 position with the lever 41being so positioned that the handle 49 (FIG. 1), that is attachedthereto, is in an intermediate position between the on and offpositions. Thus, the mechanism is constructed to provide a visualindication that the circuit breaker has tripped.

As was previously described, the circuit breaker 1 is a three-polecircuit breaker comprising only one operating mechanism 19 disposed inthe center pole compartment. Thus, only the movable contact structure 27in the center pole engages the tail portion 139 of the single releasablemember 57 to decelerate movement of the movable contact structure duringlan automatic opening operation. Since all of the movable contactstructures 27 are connected to the common tie bar 35, this deceleratingmovement of the movable contact structure in the center pole operates todecelerate movement of all of the movable contact structures in allthree of the pole units. As was previously described, during a manualoperation the contact arm structures 27 for the two outer pole units(not shown) engage suitable stop pins disposed in the outer pole unitsto limit counterclockwise movement of these contact arm structures.During an automatic opening operation, the contact arm structures forthe two outer poles engage the same stop pins disposed in the outerpoles to limit counterclockwise movement of these contact armstructures.

Before the breaker contacts can be closed following an automatic openingoperation, it is necessary to reset and relatch the mechanism. This isaccomplished by moving the handie 49 counterclockwise to the full ofiposition. During this movement, the tail portion 151 on the operatinglever 41 slides against the shoulder 149 of the releasable member 57 tothereby move the releasable member 57 counterclockwise about its pivot63. Near the end of this movement, the lower rounded portion of thelatch end 81 of the member 57 engages an outwardly extending arm of thebell-crank latch member 73 to move the latch member 73 counterclockwise.As the latch part 86 of the latch member 73 clears the corner of thenotch (not shown) in the latch rod 83, the spring 10i! restores the armS9 to its normal position moving the latch 83 to its latching position.During this movenient, the latching portion 79 of the latch "/3 is movedabove the latch end 81 of the releasable member S7 `and the latch 73 isrestrained in this latching position by engagement of the part 86thereon with the periphery of the rotary latch rod 83. Thus, when thehandle 49 is released, the latch part 81 of the releasable member 57will engage the latch part 79 of the latched main latch 73 and thestructure will be latched in the position seen in FIGURE l.

Upon the occurrence of an excessive overload or short circuit currentabove the predetermined value, the armature 12.3 (FIG. l) will beattracted to the Xed magnetic member 117 bending the bimetal 169 to theright (FIG. 1) instantaneously to thereby etlect an instantaneoustripping operation of the circuit breaker in the same mannerhereinbefore described.

In the preferred embodiment, the mechanism is constructed such that thepart 70 of the contact arm 2S engages the part 71 of the member 57 tolimit counterclockwise movement of the movable contact structure 27during an opening operation. The parts 70, 71 deform slightly at eachContact to absorb energy from the mechanical system. The mechanism canbe constructed without the stop means 70, 71, in which case thecomponent of spring force acting to rotate the member 57 clockwise willlimit counterclockwise movement of the movable contact structure 27 Thiscan be done, for example, by cutting ott portions of the members 57 and28 in the regions of the stops 71 and 70. The component of spring forceacting to rotate the member 57 clockwise is of such strength that, withthe elimination of the stop means 70, 71, the movable contact structure27 will move counterclockwise only a slight distance further than thedistance shown in FIG. 3 before the component of spring force acting torotate the member 57 clockwise will limit this counterclockwise movementof the movable contact structure 27. In all other respects the mechanismwithout the stop means 70, 71 will operate in the same mannerhereinbefore described.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe illustrated structural details and arrangement of parts may be madewithout departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit breaker comprising a stationary contact, a movable Contactstructure cooperable with said stationary contact to open and close anelectric circuit, an operating mechanism connected to said movablecont-act structure for operating said movable contact structure, saidoperating mechanism comprising a latched releasable member and resilientmeans, means operating upon the occurrence of certain overload currentconditions to release said releasable member whereupon said resilientmeans operates to move said releasable member in a lirst direction toeffect a change of the line of action of said resilient means whereuponsaid resilient means operates to move said movable contact structure toan open position, means on said releasable member to engage said movablecontact structure and to move with said movable contact structure in adirection opposite said iirst direction to decelerate opening movementof said movable contact structure during said opening movement of saidmovable Contact structure.

2. A circuit breaker comprising a stationary contact, a movable contactstructure cooperable with said stationary contact to open and close anelectric circuit, an operating mechanism connected to said movablecontact structure for operating said movable contact structure, saidoperating mechanism comprising a latched releasable member andover-center spring means, means operating upon the occurrence of certainoverload current conditions to release said releasable member whereuponsaid over-center spring means operates to move said releasable member ina first direction to effect a change of the line of action of saidover-center spring means whereupon said over-center spring meansoperates to move said movable contact structure to an open position,means on said releasable member to butt against said movable Contactstructure and to move with said movable contact structure in -a seconddirection opposite said rst direction against force exerted by saidover-center spring means to thereby decelerate opening movement of saidmovable Contact structure during said opening movement of said movablecontact structure.

3. A circuit breaker comprising a stationary contact structure, amovable contact structure cooperable with said stationary contactstructure to open and close an electric circuit, an operating mechanismconnected to said movable contact structure for operating said movablecontact structure, said operating mechanism comprising a latchedreleasable member supported on a iixed pivot, over-center spring meanssupported under tension, trip means operating upon the occurrence ofcertain overload current conditions to release said releasable memberwhereupon said over-center spring means operates to pivot saidreleasablc spring member in a first direction to thereby change the lineof action of said over-center spring means whereupon said over-centerspring means operates to move said movable Contact structure to an openposition, means on said releasable member to engage said movable contactstructure with a butt type engagement and to move with said movablecontact structure in a second direction opposite said first direction tothereby dampen said opening movement of said movable contact structure,and stop means engaged by said movable contact structure to limitmovement of said movable contact structure in the opening direction.

4. A circuit breaker comprising a stationary contact structure, amovable Contact structure cooperable with said stationary contactstructure to open and close an electric circuit, a latched releasablemember, a toggle connected at one end to said movable contact structureand at the other end to said releasable member, an operating member,over-center spring means supported between said operating member andsaid toggle, when said releasable member is latched to said operatingmember being manually operable to operate said over-center spring meansand said toggle to thereby operate said movable contact structure toopen and closed positions, trip means operating upon the occurrence ofcertain overload current conditions to release said releasable memberwhereupon said over-center spring means operates to pivot saidreleasable member in a lirst direction to change the line of action ofsaid over-center spring means whereupon said over-center spring meansoperates said toggle to move said movable contact structure to an openposition, means on said releasable member to engage said movable contactstructure with a butt-type engagement to stop said movement of saidreleasable member in said iirst direction and to thereafter move withsaid releasable member and said movable contact structure in -a seconddirection opposite said first direction against a torce exerted by saidover-center spring means to thereby decelerate opening movement of saidmovable contact structure.

5. A circuit breaker comprising a stationary contact structure, amovable contact structure cooperable with said stationary Contactstructure to open and close an electric circuit, a latched releasablemember, a toggle connected at one end to said movable contact structureand at the other end to said releasable member, an operating member,over-center spring means supported between said operating member andsaid toggle, when said releasable member is latched said operatingmember being manually operable to operate said over-center spring meansand said toggle to thereby operate said movable contact structure toopen and closed positions, trip means operating upon the occurrence ofcertain overload' current conditions to release said releasable member'whereupon said over-center spring means operates to pivotV saidreleasable member in a tirst direction to etlect a'. change of the lineof action of said over-center spring means whereupon said over-centerspring means operatesy said toggle to move said movable contactstructure to anv open position, means on said releasable member toengage said movable Contact structure during said opening movement tostop said pivotal movement of said releasable member in said firstdirection and to thereafter move with said releasable member and saidmovable contact structure in a second direction opposite said iirstdirection to thereby dampen opening movement of said movable contactstructure, and stop means on said releasable member to engage saidmovable contact structure to limit said movement of said movable contactstructure in the opening direction.

6. A circuit breakercomprising a stationary contact structure, a movableContact structure cooperable with said stationary contact structure toopen and close an electric circuit, a latched releasable member, anoperating member, spring means connecting said operating member saidmovable contact structure and said releasable member, trip meansoperable to unlatch said releasable member, when said releasable memberis latched said operating member being movable from an on position to anoft position to operate said spring means to move said movable contactstructure to an open position and said operating member being movablefrom said oli position to said on position to operate said spring meansto move said movable contact structure to a closed position, when saidreleasable member is latched and said operating member is in said onposition and. an overload current above a predetermined value occurs inthe circuit of the breaker said trip means operating automatically torelease said releasable member whereupon said spring means operates tomove said releasable member in a first direction to change the line ofaction of said spring means whereupon said spring means operates to movesaid movable contact structure to an open position and to move saidoperating member toward the ofi position, means on said releasablemember to engage said movable contact structure with a butt-typeengagement to stop said movement of said releasable member in said firstdirection and to thereafter move with said releasable member and withsaid movable contact structure in a second direction opposite said rstdirection against a force exerted by said spring means to therebydecelerate said opening movement of said movable contact structure, andmeans on said operating member to engage means on said releasable memberto stop said operating member in a position between said on and offpositions to thereby provide a visual indication that said circuitbreaker has been automatically opened.

7. A circuit breaker comprising an insulating housing having an openingtherein, a circuit breaker mechanism supported within said housing andcomprising an external handle extending through said opening, saidcircuit reaker mechanism comprising an operating member connested 'tosaid handle, a stationary Contact structure, a movable contact structurecooperable with said stationary contact structure to open and close anelectric circuit, a latched releasable member, a toggle connected at oneend to said movable contact structure and at the other end to saidreleasable member, spring means connected at one end to said operatingmember and at the other end to said toggle, trip means, when saidreleasable member is latched said handle being movable from an onposition to an ott position to move said operating member and saidspring means to operate said toggle to thereby operate said movablecontact structure to an open position and said handle being movable fromsaid oi position to said on position to move said operating member andsaid spring means to operate said toggle to move said movable Contactstructure to the closed position, when said releasable member is latchedand said handle is in said on position and an overload current above apredetermined value passes through the circuit of said breaker said tripmeans operating automatically to release said releasable memberwhereupon said spring means operates to move said releasable member in afirst direction to change the line of action of said spring meanswhereupon said spring means operates said toggle `to move said movableContact structure to an open position and a component of the force ofsaid spring means operates to move said operating member and said handletoward the oit position, means on said releasable member to engage saidmovable contact structure and to thereafter move in a second directionopposite said first direction with said movable Contact structureagainst a component of the force of said spring means to therebydecelerate opening movement of said movable contact structure, stopmeans on Said releasable member to engage means on said movable contactstructure to limit movement of said movable Contact structure in theopening direction, and means on said operating member to engage means onsaid releasable member to stop the movement of said operating memberreleasable member and movable contact structure with said operatingmember being stopped in a position such that said handle is between saidon and off positions to thereby provide an external visual indicationthat said circuit breaker has been automatically opened.

References Cited by the Examiner UNITED STATES PATENTS 2,989,606 6/1961Walker et al 2SC-116 X 3,003,046 10/1961 De Torre 200--116 X 3,134,8795/1964 Gauthier et al. 200--169 BERNARD A. GLHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

T. D, MACBLAIN, Assistant Examiner.

1. A CIRCUIT BREAKER COMPRISING A STATIONARY CONTACT, A MOVABLE CONTACTSTRUCTURE COOPERABLE WITH SAID STATIONARY CONTACT TO OPEN AND CLOSE ANELECTRIC CIRCUIT, AN OPERATING MECHANISM CONNECTED TO SAID MOVABLECONTACT STRUCTURE FOR OPERATING SAID MOVABLE CONTACT STRUCTURE, SAIDOPERATING MECHANISM COMPRISING A LATCHED RELEASABLE MEMBER AND RESILIENTMEANS, MEANS OPERATING UPON THE OCCURRENCE OF CERTAIN OVERLOAD CURRENTCONDITIONS TO RELEASE SAID RELEASABLE MEMBER WHEREUPON SAID RESILIENTMEANS OPERATES TO MOVE SAID RELEASABLE MEMBER IN A FIRST DIRECTION TOEFFECT A CHANGE OF THE LINE OF ACTION OF SAID RESILIENT MEANS WHEREUPONSAID RESILIENT MEANS OPERATES TO MOVE SAID MOVABLE CONTACT STRUCTURE TOAN OPEN POSITION, MEANS ON SAID RELEASABLE MEMBER TO ENGAGE SAID MOVABLECONTACT STRUCTURE AND TO MOVE WITH SAID MOVABLE CONTACT STRUCTURE IN ADIRECTION OPPOSITE SAID FIRST DIRECTION TO DECELERATE OPENING MOVEMENTOF SAID MOVABLE CONTACT STRUCTURE DURING SAID OPENING MOVEMENT OF SAIDMOVABLE CONTACT STRUCTURE.